1. Field of the Invention
The present invention relates to treatment of a filament yarn to produce a slub yarn, especially having a silk douppion-like configuration.
2. Description of the Related Art
Slub yarns, well known in the art, have a plurality of thicker portions along the yarn length. Such yarns are of interest because of the aesthetic properties they impart to fabric prepared therefrom.
Many proposals have been made for obtaining such slub yarns from a synthetic filament yarn. Edwards et al. U.S. Pat. No. 3,116,589, issued Jan. 7, 1964; Myers U.S. Pat. No. 3,433,007, issued Mar. 18, 1969; Joarder et al. U.S. Pat. No. 3,474,613, issued Oct. 28, 1969; and Adachi et al. U.S. Pat. No. 3,914,929, issued Oct. 28, 1975 are examples of such art.
According to these prior arts, however, the yarn is mainly treated by an air stream. This means a voluminous air consumption, resulting in high production costs. Moreover, since the process conditions are critical, it is difficult to produce various configuration yarns in accordance with changing market needs.